1. Field of the Invention
The present invention relates to a camera apparatus which executes image-pickup operation of moving picture, more particularly, to a camera apparatus which is provided with function securely preventing video picture from incurring swinging symptom even when swinging unavoidably takes place with the video camera so that stable video picture can always be realized throughout the image-pickup operation.
2. Description of Prior Arts
Recently, reflecting significant improvement of modern electronics mainly promoted by semiconductor-processing technology, remarkable progress has been achieved by consumer-use portable video camera made available in combination with video tape recorder including its compactness and light-weight construction. In addition, full automation including autofocussing function is rapidly promoted by advanced microprocessor technology, thus eventually resulting in the sharply grown demand for video camera today.
On the other hand, despite the light-weight construction of video camera, lens scale-factor still remains unchanged. Consequently, when the camera operator manually takes picture with a portable video camera, the lighter the total weight of the video camera, the greater is the vibration of the portable video camera, thus making it quite difficult for him to gain access to stable video picture by manually operating the hand-held video camera. Conversely, professional video cameras made available for broadcast stations feature complex picture-swing prevention device that stabilizes swinging video picture into normal state, which is typically comprised of means for detecting acceleration of the video camera, means for detecting the amount of displacement relative to the supporter unit mounting the video camera and the integrated unit of the video camera and the supporter unit, means for detecting difference between signal from displacement-detection means and the reference comparison signal by comparing these to each other, means for detecting relative speed between the video camera and the supporter unit, and driver means for driving the video camera by applying specific driving force which is proportional to the sum of signals from those means for detecting acceleration, comparative signal difference, and relative-speed, respectively. The picture-swing prevention device which is typically provided with those means mentioned above causes substantial inertia mass to increase in the video camera by generating specific driving force to reduce acceleration from the video camera so that the video picture can eventually be stabilized. Nevertheless, since the conventional technique used for stabilizing video picture mentioned above is mainly designed for use with automobiles, aircraft, and ships, when the camera operator desires to perform panning in the desired direction by varying the aimed direction of the video camera, the system controller also needs to vary the reference comparison signal simultaneously. Since it is practically impossible for technicians of any broadcast station to manually support both the picture-swing prevention device and a large-size professional video camera at the same time, they have nothing to do with the problem mentioned above. Conversely, when applying such a conventional video picture stabilizing technique to any consumer-use video camera featuring compact-size and light-weight for manually taking video picture, in order to properly perform panning operation the reference comparison signal should be varied. In other words, when manually operating a consumer-use video camera, the camera operator needs to support both the video camera and the picture-swing prevention device, and yet, he needs to keep controlling the reference comparison signal for varying the aimed camera direction. Compared this to any of conventional professional video cameras dispensing with compensation for the swinging video picture, it is obvious that the compact and light-weight portable video camera involves significantly complex operations.
References related to the above described prior art are Japanese Published Patent Application (Kokoku) No. 50-13030, Japanese Laid-Open Utility Model Application (Kokai) No. 56-85464, and "Vibration Isolator Servo System for TV Cameras" by Takuji Sekiguchi et al, NHK TECHNICAL REPORT, Vol. 27, No. 11 (November 1984).